1. Field of the Invention
The present invention concerns a restriction-enzyme-mapping probe for human chromosome 17.
2. General Discussion of the Background
Restriction fragment length polymorphisms (RFLPs) are different among individuals in the lengths of particular restriction fragments, Botstein, et al., Am. J. Hum. Genet., 32:314-331 (1980). As the number of known RFLPs increases, they are becoming ever more useful in the prenatal or early diagnosis of numerous hereditary diseases. RFLPs are also used in mapping a diseased gene to a specific chromosomal location, which may serve as the first step in cloning the gene.
Diseases that have been mapped by linkage studies with RFLPs include Huntington's Disease, Gusella, et al., Nature, 306:234-238 (1983); Duchenne's muscular dystrophy, Murray, et al., Nature, 542-544 (1982); X-Linked Retinitis Pigmentosa, Bhattacharya, Nature, 309:253-255 (1984); adult polycystic kidney disease, Reeders, et al., Nature, 317:542-544 (1985); and cystic fibrosis, Tsui, et al., Science, 230:1054-1056 (1985). RFLPs also have been crucial to the elucidation of mechanisms underlying hereditary cancer syndromes frequently associated with chromosome deletions such as retinoblastoma, Cavenee, Nature, 305:779-784 (1983), and Wilm's tumor, Koufos, et al., Nature, 309:170-172 (1984). In the future, RFLPs may be useful in characterizing the genetic contributions to susceptibility to common diseases which tend to cluster in families, such as colon cancer and schizophrenia, White, et al., Nature, 313:101-105 (1985). For example, U.S. Pat. No. 4,623,619 discloses a method of using a probe to determine the propensity of specific human individuals to develop atherosclerosis.
RFLPs can also provide individual-specific "fingerprints" of human DNA which can be used for such forensic purposes as identification of corpses, paternity testing, and identification of rapists. For example, Jeffreys, et al. disclosed in Nature, 316:76-79 (1985) that simple tandem-repetitive regions of DNA ("minisatellites") which are dispersed throughout the human genome frequently show substantial length polymorphism arising from unequal exchanges which alter the number of short tandem repeats in a minisatellite. The repeat elements in a subset of human minisatellites share a common 10-15 base-pair core sequence. A hybridization probe consisting of the core repeated in tandem can detect many highly polymorphic minisatellites simultaneously to provide a set of genetic markers of general use in human linkage analysis. Certain probes can detect sets of hypervariable minisatellites to produce somatically stable DNA "fingerprints" which are completely specific to an individual (or an identical twin) and can be applied directly to problems of human identification, including parenthood testing. Unfortunately, the Jeffreys, et al., probe detects repeated sequences that occur throughout the entire human genome, and gives rise to very complex electrophoresis patterns that are sometimes difficult to interpret.
Hypervariable DNA regions have been reported near the human insulin gene (Bell, et al., Nature, 295:31-35 (1982)), in the .alpha.-globin gene cluster (Higgs, et al., Nucleic Acids Res., 9:4213-4224 (1981); Proudfoot, et al., Cell, 31:553-563 (1982); Goodbourn, et al., Proc. Natl. Acad. Sci. USA, 80:5022-5026 (1983)), near the c-Ha-Ras-1 oncogene (Capon, et al., Nature, 302:33-37 (1983)) and at the telomere of the X and Y chromosomes (Cook, et al., Nature, 317:687-692 (1985)). In all cases where DNA sequence information in these regions is available, it shows that the region consists of tandemly repeated sequences which vary in copy number among chromosomes. These hypervariable regions are hypothesized to arise by mitotic or meiotic unequal crossing over or by DNA slippage during replication (Jeffreys, et al., (1985)). Hypervariable regions give rise to highly polymorphic loci at numerous genomic sites. DNA probes from such regions have been useful in paternity testing and other forensic applications as well as in human gene mapping.
It is therefore a primary object of this invention to provide a DNA probe which detects a hypervariable region of a human chromosome.
Another primary object is to provide such a probe which is specific to a single human chromosome.
Yet another primary object is to provide a probe which is easy to use and gives consistent results in forensic and medical tests.